Mechanical stoker



April 19 1927.

w. M. DUNCAN MECHANICAL STOKER Filed June l5, 1923 i t l l D C O l 0 u I O 0 t l x l 0 0 0 u m E x hw.

Patented Apr. 19, p 1927.

Uiti'fi"Ef) STATES PATENT -OF-FICE.

'WILLIAM M. DUNCAN, OF ALTO, `XLLINOIS.

MECHANICAL STOKER.

Application il'ed" June 13, 1923. Serial No. 645,026.

r-lfliis invention relates in stokers,

to improvements and more particularly Vto a mechanical stolzer provided with one or more draft boxes from which draft is :discharged through the upper portion of an endless traveling grate.

Prior to ythis invention, mechanical `stokers and especially stolers designed for forced draft have been provided with draft boxes open the top to discharge Adraft through the fuel.

in a. stolzer of this lkind, ashes and line particlesV of fuel drop through the upper portion. of the grate and open top of the draft box.

from such of ashes, etc.,

as one of been recognized lcms in this art, and expensive means have fall through thc rllie removal `diaft boxes has the difficult probvarious complex and been employed lto remove the ashes and tine fuel from-the draft The old boxes.

mechanically' operated cleaning` devices have not niet with complete success, and the relatively ysimple manually operated cleaning means is undesirable on account of the time and using the s ame. Furthermore,

labor involved in the draft box should be sealed tov prevent leakage of air under `pressure at the outlet through the like are discharged,

' and which ashes and the sealinglias licretefore been `accomplished by relatively ex aensive means including large doors hav ing accurately respondingly boxes. y

One of the objects of the is to produce an ex'lriensivc draft deliver a forcedv ther object is tol draft to provide extremely Y box structure adapted' 'to finished edges engaging coriini'slied parts of the draft present invention simple and iuthe fuel. A furfor automatic re moval ofashes and fine fuel from the draft box Without adding any expensive element to the structure.

Another object is to `seal the draft box so as to preventlealiage of draft, and to accomplish this at a minimum cost, or Without `any appreciable addition tor the costA of the appara-tus.

llVith the foregoing and other objects in view, the invention comprises the novel construction, coinbination and arrangement of parts hereinafter more specifically described ind illustrated in the accompanying dravvings wherein is shown the preferred embodiment of the invention. understood that the inven 'Hoiveveig it is to vbe tion comprehends frames, the usual :dri-ve "Wheels changes, variations and modifications Which come Within the scope of the claims -liereunto appended.

t Briefly stated, the preferred form of the invention coni-prises a draft box surrounded by an endless traveling grate, the bottom wall of the box being seated on and supported by 4the' traveling lower portion of the grate. his bottom Wall vvhas 'an outlet :means for closing the spaces. The apparatus is also designed to prevent leakage of draft vat the outlet through which ashes, etc.. are discharged from the bottom Wall'.V This Weill preferably rests .upon the. lioiver porti-on ef lthe girate, and the' :line material' discharged into this part ef the grate serves as a seal to prevent leakage of draft through the outlet. fis a further safeguard, a ingv plate is preferably located `belowr fthe draft box -Where it centacts with the leave-r portion of the traveling .grate to support the saine and at the saine time confine the ashes 'below the draft box Where .they serve as a seal 'fer the ash outlet in the Ai'ioatn bottoni Wall. By con-ibiiiing` lthe seveial elements as herein pointed out the structure is renderedself-cleaning and self-sealing, and this isv accomplished iii a draft box structure which is evidently simpler and lessexpensive than the ordi-nary structures Without -the mechanical sealing and cleaning features.

Fig. I is a longitudinal section illustrating a mechanical stole-er embodying the fea.-

tu-res of this invention.

Fig. Il is a transverse section taken approximately on the line II-H in To illustrate the invention I have'sheivn a portion of a. furnace provided with side Walls 1 between which the stolcer is mounted on Wheels 2. `The stolrer comprisesside fra-nies 3 in which the vv-heelsV 2I are mounted, an endless chainA grate i betnveen the` side 5 mounted on a power shaft G at the front ends of the side frames, and the usual idle roll 7 at the rear of the side frames. The shaft 6 can be driven by any suitable means to cause the upper portion of the grate to travel toward the rear of the furnace, while the lower portion of the grate moves toward the front. 9 designates a. fuel hopper located at the front of the stoker to discharge fuel onto the top of the traveling grate.

Partitions 9, surrounded by the endless grate, are connected by means of bars 1() to the side frames 8 so as to form the side walls of a series of draft boxes. The end walls of these boxes are formed by the side frames Si which support the partitions 9.

rlhe bottom walls of the several draft boxes are formed by a long plate 11 located below and separated from the lower-edges of the partitions 9. The plate 11 is approximately as wide as the grate. but its side edges are preferably separated a slight distance from the side frames 3, as it would be difficult and expensive to closely lit the plate to the side frames. Instead of being attached to the side frames or to the partitions 9, the plate 11 rests upon and is supported by the lower portion of the t aveling chain grate. To aid in forming ash seals which will be hereafter described, and also to limit the motion of plate 11, angle bars 12 are riveted to said plate, and the upper margins of some of these angle bars are arranged to engage abutments formed by the lower edges of partitions 9. 1t is not necessary for all of the bars 12 to engage partitions 9.

A forced draft may be supplied through a conductor 18 (Fig. 1I) at one side of the 'furnace` each draft box being provided with telescoping intake tubes 111v and 15 extending from said conductor to one of the side frames. The draft forced into lthe draft boxes is permitted to pass out through the open upper sides thereof, and thence through the upper portion of the grate to the fuel supported thereon.

Ashes and tine fuel drop through the upper portion of the chain grate and fall onto the long plate 11 which forms the bottoms of the draft boxes. This plate has outlet openings 1G through which the ashes, etc.7 are discharged into the lower portion of the traveling grate. In actual practice. the ashes will usually lie in angular piles as suggested in the drawings, each pile being inclined downwardly toward a discharge opening 16. The openings 16 may be narrow, but they are preferably elongated as shown by Fig. H, so as to extend almost entirely from end to end of the draft boxes.

l will now point out the manner in which the draft boxes may be sealed to prevent leakage of draft at their lower corners. The partitions 9 terminate above the bottom plate 11, but the piles of ashes and fine fue] accumulate at the partitions to form seals preventing leakage of draft through the spaces below said partitions. This is accomplished by locating the discharge openings 16 at points remote from the partitions 9, and the seals are rendered more effective by the angle bars 12 serving as baffles for the ashes. As a further safeguard, Z-bars 17 maybe secured to partitions 9 so as to form inverted pockets in which the upper edges of angle ,bars are arranged. rllhe battles produced in this manner serve to confine ashes, etc., which form seals to prevent escape of draft. I have shown the Z-bars 17 on the partitions 9 at the rear portions of the grate where the ashes are relatively fine and more likely to be blown through the spaces between bars 12 and partitions 9.

The side edges of bottom plate 11 are separated from the side frames 3, and these frames extend downwardly to points beyond said bottom plate, as shown in Fig. ll. Angle bars 18 are secured to theside frames so as to overlie the spaces at the side edges of the bottom plate 11, and these bars serve as baflles preventing free escape of ashes and fine fuel at said spaces. lThis results in the production of seals at the lower end corners of the draft boxes.`

The lower portion of the traveling chain grate is supported by a long plate 19 resting upon rods 2O which extend through the side frames 3, and longitudinal motion of this plate is prevented by lugs 21 extending from the plate and engaging two of the rods 2O7 as shown in Fig. I. The plate 19Y lies directly below plate 11 and it extends from the front to the rear of the grate. lt also extends from one side frame 3 to the other.

In addition Vto serving as a substantial supporty for the lower portion of the flexible chain grate, the plate 19 cooperates with the plate 11 to form a passageway through which the grate travels. rllhe ashes and other material discharged through openings 16, at the bottoms of the draftboxes. enter into this passageway and are carried to the front of plate 19 where they are permitted to drop from the chain grate. The plate 19 may be termed a sealing plate, for it confines the ashes, etc., in the chain grate so as to form a seal which prevents any material leakage of draft through the openings 16 where the ashes and tine fuel are discharged from the draft boxes.

The upper portion of 4the chain grate may be supported by long bars 23 resting upon the upper edges of partitions 9, and also by angle bars 24 secured to the partitions.

I claim:

1. A mechanical stoker comprising an endless traveling chain grate, a draft box surrounded by said traveling grate, the top of said draft box being open to discharge draftthrough the upper portion of said erateaand .thebttomvall 0f Seid. feti box being in contact with andsupported by the lower portion of said traveling grate.

A mechanical Stoker comprising an endless travelherhan erster. a draft box surrounded by said traveling grate, thetop' of said ,draftL box` being open to discharge draft through upper portion of Said grate, and bottom wall of said diaftbox being in contact with and Supported by the .lower portion of said traveling grate, and abutments limiting the motion of said bottoni wall.

3. A mechanical Stoker comprising an endless traveling chain grate, a draft box surrounded by Said traveling grate, the top of said draft box being open to discharge draft through the upper portion of said grate, and the bottom wall of said draft box being in contact with and supported by the lower portion of said traveling grate, said bottom wall being arranged to receive the material falling through the upper portion of the grate and provided with an outlet for the discharge of said .material into the lower portion of the traveling grate.

Ll. A mechanical stoker comprising an endless traveling chain grate, a draftbox surrounded by said traveling grate, the top of said draft box being open to discharge draft through the upper portion of said grate, and the bottom wall of said draft box being in contact with and supported by the lower portion of said traveling grate, said bottom wall being spaced from the side walls of the draft box and the draft box being provided with means to prevent free escape of ashes at the spaces.

5. A mechanical Stoker comp ising an endless traveling chain grate, a draft box surrounded by said traveling grate, the top of said draftvbox being open to discharge draft through the upper portion of said grate, and the bottom wall of said draft box boing in contact with and supported by the lower portion of said traveling grate, said bottoni wall being spaced from the side walls of the draft box and the draft box beingl provided with baffles to prevent free escape of ashes at the spaces.

A mechanical Stoker comprising an endless traveling chain grate, a draft box surrounded by said traveling grate, the top of said draft box being open to discharge draft through the upper portion of said ojrate, and the bottom wall of said draft box icing in contact with and Supported by the lower portion of said traveling grate, said draft box having end walls extending downwardly beyond said bottom wall, said end walls being spaced from said bottom wall and provided with means to prevent free escape of ashes at the spaces.

7. A mechanical Stoker comprising an endless traveling chain grate, a draft box `nriounded by said traveling grate, the top of vsaid draft box being open to discharge draft through the upper portion of said ite, Ythelbottom' fwall of said draft bei in Contact with and supported by Vtl cglowe v po'ition of 'said travelling grate` said bottom vwall 'being located entirely be low 'the Yside walls of the "aft box and int' posedb'etween ythe end walls thereof, said bottom livaill being spaced frinsaid Side and end walls and the draft box being provided with baflies to prevent free escape of ashes at the Spaces.

8. A mechanical stoker comprising an endless traveling chain grate, draft boxes surrounded by Said traveling chain grate, the top of each draft box being open to discharge draft through the upper portion of said grate, and a continuous plate forming the bottom walls of said plate being in contact with and supported by the lower portion of Said traveling grate.

9. A mechanical stoker comprising an endless traveling chain grate, draft boxes surrounded by said traveling chain grate, the top of each draft box being open to discharge draft through the upper portion of said grate, and a continuous plate forming the bottom walls of said draft boxes, said plate being in contact with and supported by the lower portion of said traveling grate, said plate being arranged to receive the material falling through the upper portion of the grate and provided with an outlet in each draft box for the discharge of said material into the lower portion of the traveling grate. l

10. A mechanical stoker endless traveling chain grate, a draft box surrounded by said traveling grate, the top of said draft box being open to discharge draft through the upper portion of said grate, the bottom wall of said draft box being arranged to receive material falling from the upper portion of the gra-te, said bottom wall being adjacent to the lower portion of the traveling grate and provided with an outlet for the discharge of said material into Said lower portion, and a sealing plate located directly below the draft box and in contact with the bottom face of the grate so as to support the outgoing mate-rial below comprising an the draft box, said bottom wall being seated on and supported by the lower portion of the traveling grate, and said lower portion being Supported by Said sealing plate.

1l. A mechanical stoker comprising an endless traveling chain grate having a fuelsupporting upper portion, a lower portion directly below said upper portion, a part of said lower portion being exposed to receive granular material dropping from the fuel, an air chamber being formed between draft boxes, said said upper and lower1 portions to provide for the admission of draft to the fuel7 sealing means at the lower corners of said chamber to eenline the draft therein, said sealing means including' baliles arranged longitudinally of the grate and located above and adjacent to the side margins of said lower portion to obstruct the granular material, and tailles arranged transversely ot' the grate and extending from one of said side margins to the other, said balles being adapted to cooperate with the granular material to form the seals in said lower corners7 and sealing means located below and in Contact with the lower portion oi"l the grate to prevent free escape of draft through said lower portion.

ln testimony that I claim the foregoing l hereunto affix my signature.

WILLIAM M. DUNCAN. 

